Sheet guiding apparatus



June 25, 1963 G. P. TAlLLlE 3,095,194.

SHEET GUIDING APPARATUS -Filed March 1, 1962 5 Sheets-Sheet 1 FIG. 1

INVENTOR. GORDON P. TAILLIE A T TORNEY June 25, 1963 G. P. TAILLIE3,095,194

SHEET GUIDING APPARATUS Filed March 1, 1962 3 Sheets-Sheet 2 INVENTOR.GORDON P. TAILLIE A T TORNE V June 25, 1963 e. P. TAILLIE 3,095,194

SHEET GUIDING APPARATUS I Filed March 1, 1962 3 Sheets-Sheet 3 INVENTORGORDON P. TAILLIE yaw/Jud A T TOR/VEV i tats atnt 3,t35,194 SHEET GUEDMGAETARATUS Gordon P. Taiilie, Rochester, N321, assignor to Xeroxgorgoration, Rochester, NE! a corporation of New Filed Mar. 1, 1962,Ser. No. 176,530 3 Claims. (Cl. 271-7?) This invention relates to paperguide rolls for use in the sheet conveyor mechanism of a Xerographicrepro- 1O material to form a powder image of the copy on thi drum. Thepowder image is then transferred to a sheet of support or transfermaterial, usually paper.

Thus, in the field of Xerography, an image is developed on a Xerographicplate, the image being secured to the xerographic plate by anelectrostatic force only, and within the influence of this electrostaticforce the image can very easily be smeared or smudged. In the transferprocess, a sheet of support material is brought into contact with theimage on the Xerographic plate and the image is then transferred andheld electrostatically on the support material. Unlike many types ofmechanical forces, the electrostatic forces binding the image bodyeither to the Xerographic plate or later to the support material arecomparatively weak in preventing lateral motion of the image body awayfrom the xerographic plate surface or from the surface of the material.

When transfer is to be effected from a moving xerographic plate onto asupport material in an automatic xerographic reproducing machine, thesupport surface must be moved into contact with the xerographic platefor synchronous movement therewith during the transfer process to permitproper registered image transfer from the plate to the support material.If relative movement between the plate and support material is permittedalong the areas of transfer contact, smearing or smudging of the imageswill occur.

One type of conveyor mechanism employed in Xerographic reproducingapparatus for conveying sheet support material from a receiving stationinto transfer contact with a xerographic plate and then to a deliverystation is disclosed in copending application Serial No. 46,463, filedAugust 1, 1960, in the name of Robert A. Hunt and Gordon P. Taillie.Such an arrangement includes a pair of endless chains, or equivalents,sprockets,

or equivalents, for supporting the chains, and at least one sheetgripper connected to the chains at right angles to their path ofmovement, for movement through a closed circuit from a receiving stationto a delivery station. Heretofore, this type of conveyor mechanism hasproved satisfactory for use in Xerographic apparatus, provided theconveyor mechanism is of such a length as to permit a substantially longstraight run of sheet material to and from the xerographic plate toensure a uniform rate of travel of the sheet material.

It is apparent then that the side of the conveyor mechanism of this typegoverns the size of the Xerographic apparatus; that is, the bigger thesheet of support material conveyed by the conveyor, the longer thelength of the conveyor, and therefore, the greater the outside physicaldimension of the entire Xerographic apparatus. Furthermore, the greaterthe length of travel required for a sheet of transfer material, thegreater the period of time required for making a Xerographicreproduction on the support material before it is fed from the machine.It is, therefore, an object of this invention to improve paper guidemeans for use in endless belt type sheet conveyors to permit the overalllength of a sheet conveyor to be reduced while still permitting uniformtravel of a sheet material conveyed thereby.

Another object of this invention is to improve paper guide rolls toguide sheet material around a turn in a conveyor mechanism at a uniformrate of speed.

It is a further object of this invention to improve paper guide rolls sothat a malfunction of the paper guide roll will not interfere with theoperation of the sheet conveyor mechanism.

It is a further object of this invention to improve paper guide rolls sothat they are economical to produce, reliable in operation, and willfail safe if malfunction occurs.

These and other objects of the invention are attained by means of aguide plate that is freely rotatable to permit passage of a sheetgripper mechanism and biasing means on the guide plate to return theplate to a position supporting the sheet of material received by thegripper mechanism. Failure of the biasing means will leave the guideplate in a position that will not interfere with the path of travel ofthe next succeeding gripper mechanism. Thus, this arrangement provides adevice that, even under failure of one of the parts, will not interferewith the operation of the machine.

The invention is disclosed in the appended drawings, in which:

FIG. 1 is a schematic illustration of a type of Xerographic reproducingmachine in which the present invention may advantageously be employed;

FIG. 2 is a perspective view of a sheet conveyor system embodying thepresent invention;

FIG. 3 is a sectional view of the paper guide roll taken along line 33of FIG. 2;

FIG. 4 is a sectional view of the paper guide roll of PEG. 3, shown in adeflected position; and,

FIGS. 5 and 6 are sectional views similar to FIGS. 3 and 4, showing analternate embodiment of the invention.

Referring now to FIG. 1, there is shown a continuous Xerographicreproduction machine of the type disclosed in the above-mentionedcopending application in which a paper guide roll may advantageously beemployed. The Xerographic apparatus comprises a Xerographic plate 10,including a photoconductive layer of light receiving surface on aconductive backing and formed in the shape of a drum, which ispositioned on a shaft *11 journaled in a frame (not shown) to rotate inthe direction indicated by the arrow to cause the drum surfacesequentially to pass a plurality of Xerographic processing stations.

For the purpose of the present disclosure, several xerographicprocessing stations in the path of movement on the surface may bedescribed functionally, as follows:

A charging station A, at which a uniform electrostatic charge isdeposited on the photoconductive layer of the Xerographic drum;

An exposure station B, at which a light or radiation pattern of copy tobe reproduced is projected onto the drum surface to dissipate the drumcharge on the exposed areas thereof, and thereby form a latentelectrostatic image on the copy to be reproduced;

A developing station C, at which a xerographic developing materialincluding toner particles having an electro static charge opposite tothat of the electrostatic latent image are cascaded over the drumsurface, whereby the toner particles adhere to the electrostatic imageto form a xerograp-hic powder image in the configuration of the copy tobe reproduced;

A transfer station D, at which the xerographic powder image iselectrostatically transferred from the drum surface to a transfermaterial or support surface; and,

A drum cleaning and discharge station E, at which the drum surface isbrushed to remove residual toner particles remaining on the drum afterimage transfer, and at which the drum surface is exposed to a relativelybright light source to effect substantially complete discharge of anyresidual electrostatic charge thereon.

At charging station A, a corona discharge array 12 of one or moredischarge electrodes, that extend transversely across the drum surfaceand are energized from a high potential source, are substantiallyenclosed within a shielding member. The charging apparatus may be of thetype disclosed in Walkup Patent 2,777,957.

Next subsequent thereto in the path of motion of the xerographic drum isexposure station B, which contains an optical scanning or projectionmechanism generally designated 13 and a light shield member 14. Theoptical scanning mechanism consists of a lamp LMP1 which provides auniform lighting source of projecting a li ht image of a film 13, orother copy to be reproduced. Projector 14 contains a series of opticallenses which project the image onto an object mirror 16 in light shield14. Object mirror 16 reflects the image through aperture 17 onto thesurface of the rotating xerographic drum. In the commercial form of thismachine, a film holder (not shown) is inserted between lamp LMPl andprojector 15, and is supported by a movable carriage on the projector.The film holder is arranged for movement in a path to traverse theoptical path of the lens whereby the subject image of the film isscanned in timed relation to the movement of the light receiving surfaceof the xerogr'aphic drum and a [light corresponding to the subject imageis transferred to the surface of the xerographic drum.

Adjacent to the exposure station is a developing station in which thereis positioned a housing 18 for containing a suitable two componentdeveloping apparatus. In this arrangement, a bucket-type conveyor 20having a suitable driving means (not shown) is used to carry developingmaterial 21 to the upper part of the housing where it is cascaded downover a chute 22 onto the xerographic drum.

As the developing material is cascaded over the xerographic drum, tonerparticles are pulled away from the carrier component of the developingmaterial and deposited on the drum to form powder images. The carriercomponents pass off the drum into the lower portion of housing 18, forrecycling. As powder images are formed, additional toner material may besupplied to the developing material in proportion to the amount of tonerdeposited on the drum surface. For thi purpose, there is provided acontainer 23 for toner '24 to be added to the developing material 'at arate determined by a control gate 25 After passing developing station C,the xerographic drum rotates past image transfer station D. At thetransfer station, a sheet feeding mechanism is adapted to feed sheets oftransfer material, usually paper, successively to the xerographic druminregistration with the formed xerographic powder image on the said drum.

In the embodiment shown, the sheet feeding mechanism includes a chainconveyor 26 carrying one or more paper grippers 27 in a circuit betweensheet feeding station 79 and a sheet delivery station 71. Means areprovided to activate the grippers to cause the grippers to take hold ofthe front edge of a sheet of support material 28 inserted into themachine at the station '74 and to hold the sheet while traveling to thedelivery station and there to release the sheet for removal from themachine. In the embodiment shown, a sheet of transfer material is fedmanually by an operator to paper gripper 27 and is forwarded by thepaper gripper into contact with a xerographic drum at image transferstation D.

The transfer of a xerographic powder image from the drum surface to thesupport material is eifected by i means of a corona transfer device 29located at or immediately after the point of cont-act of the supportmaterial and the xerographic drum. The corona transfer device issubstantially similar to the corona discharge device 12 that is employedat charging station A, in that it includes an array of one or morecorona discharge electrodes that are energized from a suitable highpotential source and extend transversely across the drum surface and aresubstantially enclosed within a shielding member. In operation, theelectrostatic field created by the corona discharge device is effectiveto cause the transfer material to electrostatically adhere to the drumsurface, whereby the transfer material moves synchronously with the drumsurface in contact therewith. The electrostatic field i also effectiveto attract the toner particles comprising the powder image from the drumsurface and cause them to adhere electrostatically to the surface of thetransfer mate'rial.

As the paper gripper is advanced by the chain conveyor it strips thesheet of transfer material from the drum and transports it to a fixingdevice, such as a heat fuser 30, where the xerognaphic powder imagespreviously transferred to the support surface are permanently fixedthereto. Suitable support rods 31 are provided to guide the trailingedge of the sheet of support material in proper relation to the heatfuser. The heat fuser 34} contains electrical heating elements R1, R2,and R3, which are connected to a suitable source of power (not shown).

After fusing, the finished copy is discharged from the apparatus at asheet delivery station 71. To accomplish this, there is provided a pairof delivery rollers 32 and 33 which receive the sheet from a papergripper and deliver it to a collecting tray 34;

After the image is transferred from the xerographic drum to the supportsurface, the xerographic drum rotates past the cleaning station E toremove any residual charge and developing material that may remain onthe xerographic drum. The corona precleaning device 35, similar tocorona charging device 12, is positioned to impose an electrostaticcharge of suitable polarity on the drum and powder adherent thereto, toaid in effecting removal of the powder from the drum surface. Arotatable brush 35 is positioned to eifect removal of this residualpowder from the drum and a source of light [such as LMPZ floods the drumsurface with light to cause dissipation of any residual electric chargeremaining on the drum. For collecting the powder particles removed bythe brush there is provided a dust hood 37.

For removing dust particles from the brush and dust hood, an exhaustduct 38 is arranged to cover a slot that extends transversely across thehood 37 and is connected to a filter bag 39 in a filter box 49. Motordriven fan units 41 connected to the filter box, produce a flow of airthrough the filter box drawing air through the area surrounding thexerogr aphic drum and the dust hood, the air entrains powder particlesremoved from the drum by the brush as the air flows through the dusthood. Powder particles are separated from the air as it flows throughthe filter bag so that only clean air reaches the motor fan unit.

Any residual electric charge remaining on the Xerographic drum isdissipated by light from fluorescentlamp LMPZ, mounted in lamp housing42. A suitable power source is provided for energizing the fluorescentlamp.

Operation of the paper conveyor is effected by actuation of a limitswitch LS1, upon the insertion of a sheet of transfer material into apaper gripper, and the operation of the paper conveyor is terminated,after a sheet of transfer material has been conveyed from the front ofthe machine to the delivery rollers, by limit switch LS2 which isactuated by one of a pairof actuators 42 on the paper conveyor. As thepaper conveyor is operated, the actuator 42 contacts limit switches LS3and LS4 which are used to effect the operation of the projectionapparatus.

Referring now to FIG. 2, the conveyor chains 26 ar mounted on pairs ofsprockets 43, 44, 45, 46 and 47, which are rotatably mounted on shaftsbetween side frame members 48 and 49. Each gripper bar 27 is mounted onchains 26 and is carried in a continuous path around each of thesprockets back to the original position as shown in FIG. 2. Mountedbetween the pair of sprockets 46 on shaft 50 which is fastened at itsends in the plates 48 and 49, is a paper guide roll 51 which constitutesthe essence of this inventtion. As shown in FIGS. 2 and 3, paper guideroll 51 consists of a guide plate 55 mounted on a pair of spacers 52which are rigidly secured to shaft 56 by means of set screws 54. Paperguide roll 51 is pivotally mounted on spacers 52 by means of pin 53.

Guide plate 55 is formed with a circular portion covering an arc ofapproximately 90 and a fiat portion extending from :the circular portionin the direction of the front of the machine. On the end of the flatportion is a counterweight 56 attached by means of rivets 57. Guideplate 55 is freely rotatable on pin 53 and is normally pivoted, by thecounterweight 56, which is secured to the underside of the flat portionof guide plate 55, so that the fiat portion extends downward toward thefront of the machine. That is, guide plate 55 is in such a position thatthe flat portion is at an angle to the path of travel of the gripper bar27, and the circular portion of guide plate 55 is in interferencerelationship with the gripper bar 27 as it travels in its normal patharound sprockets 46.

The freedom of movement of the guide plate 55 on pin 53 permits thegripper bar 27 to deflect the guide plate from its normally biasedposition and allows gripper bar 27 to pass around sprockets 46, at whichpoint counterweight 56 causes the guide plate 55 to return to its biasedposition as shown in FIG. 3. The guide plate forms an elongated singleguide for a sheet of transfer material, the radius of the peripheralsurface of the guide being equal to the pitch radius of the sprockets 46for the purpose as to be described hereinafter.

While the sheet of transfer material is being pulled at one end by thepaper gripper and held back at its other end by the tacking force ontothe xerographic drum, the paper guide roll will remain rotatedsubstantially in the position shown in FIG. 4, until the paper gripper27 passes over sprockets 46, at which point the paper guide roll returnsto its normally biased position, as shown in FIG. 3, and provides aguide path for the sheet of transfer material. If the guide roll werenot present, the distance between the forward edge of the sheet ofmaterial and the contact with the xerographic drum would be shortened asthe gripper bar passes around sprockets 46. However, the guide rollprovides a surface for the material to pass over and still maintain .thesame tension on the support surface by the gripper bar as if the gripperbar were traveling in a straight path away from the xerographic drum.

FIGS. 5 and 6 show another embodiment of the invention. The paper guideroll 58 is formed in the same manner as that described in the preferredembodiment, that is, it includes a segment of a circle and a flatportion extending toward the front of the machine. Spacer plates 59,secured to shaft 50 by means of set screws 60, contain a pin 61 to whichguide plate 58 is rotatably attached. A tension spring 62 is secured tospacer 59 and to the end of the flat portion of guide plate 58. Spring62 causes the guide plate 58 to be held in a normally biased positionsuch that the flat portion is at an angle to the path of travel ofgripper bar 27.

In operation, in the same manner as previously described, the gripperbar 27 comes in contact with guide plate 58 and deflects the guide plateinto the position shown in FIG. 6. Guide plate 58 is deflected aroundpin 61 permitting f-ree passage of gripper bar 27 and extending tensionspring 62. After the gripper bar passes around sprocket 46, guide plate58 is free to return to its nor- 6 mally biased position by means oftension spring 62 and provides a surface over which the support materialmay pass without shortening the distance between the gripper bar and thepoint of contact with the xerographic drum.

Spacers 59 contain limiting pins 72 and 63. Limiting pin 72 regulatesthe normally biased position of guide plate 58 and limiting pin 63regulates the position of guide plate 58 in the deflected position.Limiting pin 63 is a fail-safe device such that, should tension spring62 fail, the normal weight of guide plate 63 would cause the plate tocome to rest on pin 63. Thus, the guide plate would remain in a positionpermitting the passage of paper gripper 27. Without pin 63, should thetension spring 62 fail, the guide plate under its normal weight wouldswing in such a position that the gripper bar would come in contact withthe underside of the flat portion of the plate 53 and would jam, causingdamage to the machine and possibly stalling the movement of the gripperbar. Continuous movement of the gripper bar is necessary since at thispoint, a portion of the transfer material is passing under the heatfuser 30. Any restriction in its normal movement would delay themovement of the transfer material and cause excessive heating andpossible fire.

In the normal operation of the machine, a microfilm card is placed inprojection 15, an image of which is projected by means of LMPl throughprojector 15, mirror 16 onto xerographic drum 10. A sheet of transfermaterial or support surface, is inserted into the machine at feedingstation 70 and activates limiting switch LS1, so that gripper bar 27will grip the sheet of transfer material and carry it into contact withthe xerographic drum at image transfer station D. The electrostaticimage on the drum is developed at developing station C, and transferredto the sheet of transfer material at station D. Gripper bar 27 thencarries the sheet of transfer material in spaced relation to the heatfuser 30. After passing under the heat fuser 30, the gripper bar comesinto interference contact with guide plate 58 and causes the guide plateto rotate about pin 53. The sheet of transfer material passes betweenrollers 32 and 33 at which point the gripper bar releases the sheet oftransfer material. Guide plate 55 returns to its normally biasedposition where it serves as a guide surface for the sheet of transfermaterial. Roller 33 and idler roller 32 move the transfer material anddeposit it in tray 34.

Although the invention, in each of its forms is described as used with aconveyor system of an automatic xerographic reproduction machine, itwill be apparent to those skilled in this or related arts that it mayreadily be applied to any system in which it is required to handlesheets of material by means of a conveyor system. Therefore, since manychanges could be made in the above construction and many apparentlywidely different embodiments of this invention could be made withoutdeparting from the scope thereof, it is intended that all mattercontained in the specification and drawings be interpreted asillustrative and not in a limiting sense.

What is claimed is:

1. In a sheet conveyor mechanism including a pair of endless chainsmounted on parallel pairs of sprockets and a sheet gripper mechanismmounted on said endless chains,

a sheet guide roll means consisting of an arcuate guide plate having aflat segment in interference relation with the path of travel of thegripper mechanism,

said guide plate being pivotably mounted on one or more collars rigidlysecured to a shaft between a pair of said parallel sprockets,

and a counterweight positioned on the underneath side of said fiatsegment to position the arcuate section coincidental with the pitchcircle of said sprockets.

2. In a sheet conveyor system including a sheet gripper mechanismmounted on a pair of endless chains that move in a path around a seriesof parallel sprockets,

a sheet guide roll consisting of a plurality of collars rigidly mountedon a shaft between a pair of said sprockets, a pin mounted on each ofsaid collars, an arcuate guide plate pivotably mounted on said pins,said guide plate having a curved peripheral section equal to the pitchcircle of said sprockets and a flat segment attached to said curvedsection, and spring means connected to said flat section and to saidcollars to normally bias said guide plate in a position wherein saidcurved section is coincidental with the pitch circle of said sprocketsand said flat section is in interference relation with the path of 152,392,391

travel with said gripper mechanism.

3. The apparatus of claim 2, wherein said collars contain twopositioning pins, said pins extending outwardly in interferencerelationship with the pivotable movement of said guide plate, and saidpins positioned on said collar to limit the maximum movement of saidguide plate, whereby, upon failure of said spring means, the movement ofsaid guide plate will be limited by, said positioning pins and will notinterfere with the movement of said gripper mechanism.

References Cited in the file of this patent UNITED STATES PATENTS2,198,385 Harrold Apr. 23, 1940 Kaddleland Jan. 8, 1946 2,775,934 Luehrset a1. Ian. 1, 1957

1. IN A SHEET CONVEYOR MECHANISM INCLUDING A PAIR OF ENDLESS CHAINSMOUNTED ON PARALLEL PAIRS OF SPROCKETS AND A SHEET GRIPPER MECHANISMMOUNTED ON SAID ENDLESS CHAINS, A SHEET GUIDE ROLL MEANS CONSISTING OFAN ARCUATE GUIDE PLATE HAVING A FLAT SEGMENT IN INTERFERENCE RELATIONWITH THE PATH OF TRAVEL OF THE GRIPPER MECHANISM, SAID GUIDE PLATE BEINGPIVOTABLY MOUNTED ON ONE OR MORE COLLARS RIGIDLY SECURED TO A SHAFTBETWEEN A PAIR OF SAID PARALLEL SPROCKETS, AND A COUNTERWEIGHTPOSITIONED ON THE UNDERNEATH SIDE OF SAID FLAT SEGMENT TO POSITION THEARCUATE SECTION COINCIDENTAL WITH THE PITCH CIRCLE OF SAID SPROCKETS.